Repair of ARCOY power plane

[boater sam]

I wish that everything was repairable in the 3rd world Ted.
I see piles of CRTs in ditches near junkyards here. Wish I could ship them.
I had many small induction motors rewound for washers, dishwashers, duct fans etc but I cannot remember when I last got an armature rewound in the UK, must be 50 years at least. I rewind field coils in brush motors but its usually the armature that is burnt.
The generator business keeps the local re-winders working in the main I found.
In Africa I remember seeing fridge motors being re-wound and then the tops welded back on, never seen that anywhere else. But fridge repairs here are common with a blowlamp to braze the pipework, you can buy a disposable can of refrigerant.

[TNC]

Just out of interest, can someone please advise whether solder between the armature segments (as seen in my photo) would affect performance?

[ppppenguin]

That solder (or whatever else it might be) between the armature segments should not be there. The spaces bewtween the segments should be open slots.

Could it be some attempt at balancing the armature? Though I thought that was normally done by drilling or grinding small amounts off a pole that's too heavy.

[Crackle]

Trevor, how could solder have got in that location, where would it have come from? I wonder if it may be there to help balance the armature.

Mike

[TNC]

Well Mike, I was similarly puzzled...and the only explanation I could come up with is that maybe the machine had been regularly overloaded and therefore overheated and that that had caused the solder in the commutator area to soften and under centrifugal force migrate to this new position.
Jeffrey in his previous post states "it should not be there" but going further I wonder if, in that place, it manages to conduct, then might that cause fatal interference in the magnetic functioning/fluxing of the armature's poles?

Clearly wE need the views of an expert in electric motors!

[ppppenguin]

The person we need is Ed Dinning.

[boater sam]

Most late armatures have the winding ends spot crimped into a groove in the commutator segment. No solder used.
They used to be soldered.
If the commutator has been overheated any solder will have been flung out, the carbon brushes will smear it into the commutator gaps.
If this is the case I would expect to find some solder splatter in the field coil or rear housing.
Clean out all the gaps thoroughly down to the insulation.
Check the insulation of the segments to the steel core, if it is good, check the continuity of each coil between adjacent segments, you will get a low reading which must be the same all round the commutator.
If you get a higher reading between 2 segments, that coil is O/C, you see the resistance of all the other coils in series instead.

[Ed_Dinning]

Hi Folks, a good reply by Sam. For shorts within the armature winding an AC "Growler " works well if you can find one.
It is not unknown for a wire to break under the "banding" (sometimes string) that covers the riser wires from the comm to the actual winding in the slots.
This usually leaves tell-tale signs on the comm.

Ed

[ex 2 Base]

Armature fault location. First go around all the commutator segments with a ground down thin hacksaw blade, possibly dislodging any short circuits, bits of solder and carbon dust. In the past GROWLERS were used to locate armature faults, these are a thing of the past as are magneto re-magnetisers. Larger garages had growlers to test dynamo armatures, now all modern cars have alternators. For those who have access to a milling machine it is possible to make a growler. A growler is part of a transformer, which has had its secondary winding removed. A vee is machined away in which to lay an armature, the armature forms the secondary of the transformer. When the armature is in position and power is switch on to the transformer primary, and a feeler gauge or thin hacksaw blade is held very slightly above the armature a buzzing sound is made as the armature is rotated. If there is a short circuit a large current will flow and the blade will be pulled sharply down onto the armature laminations. Specialist motor bike and classic car restoration people have growlers, if however a growler isn’t available, below is a test you can do. This test is often much better, (its known as drop test), you need a 12 volt battery and a 24 watt bulb, connected one side of the battery to one side of the bulb. Using an elastic band wrapped around the commutator attach one end of the battery and one lead from the bulb, both about 120˚ apart. Using a centre zero milli ammeter fitted with two probes, move around the commutator one segment at a time, (mark where you have tested with a felt tip pen). If the armature is sound, all indications will be the same. If you get an abnormally high indication you have a faulty connection, which might be fixed. If all you have is a milli ammeter then you need to switch the probes around as you go. An AVO is ideal but you do have to switch leads, I think better than a digital type, but not everyone has both types Don’t forget armatures can also have earth faults, which are difficult to locate. Again using an elastic band connect one lead to the commutator and the other to the shaft, hopefully you’ll get an infinity reading or very close. Arcoy were very well made tools so I would hunt around hoping to locate a re- winder who has the expertise to wind the armature and importantly balance it afterward. I thought you may like to read the above, its worked for me in the past.Ted